Reduction in Capacitor Mounting Area! - Introduction of a case examining the part optimization utilizing simulation -

 

Reduction in Capacitor Mounting Area!
- Introduction of a case examining the part optimization utilizing simulation -

2022-09-23

  1. Demands and issues in application design
  2. Proposal case using hybrid capacitors
  3. Summary
  4. Related product information
  5. Related information
  6. Tags related to this article

For customers involved in automotive applications, shortening the development period and making applications more compact are always major issues. Panasonic offers a wide range of products to help solve these problems that circuit and board designers face. This article introduces a case in which Panasonic's conductive polymer hybrid aluminum electrolytic capacitors(hereinafter referred to as hybrid capacitors) have solved problems in the design of control and motor system applications.

Demands and issues in application design

Panasonic's hybrid capacitors are widely used as input and output capacitors in DC/DC power supply circuits in automotive applications. The following are specific examples of what circuit and board design engineers of application manufacturers are having problems regarding requests from upstream clients.

  • The voltage fluctuation at the time of load change needs to be minimized while maintaining the conventional size.
  • It takes time to select the optimal parts and evaluate their replacement in order to make applications lighter and more compact.

In addition, even during the stage for actually designing the board, we sometimes hear the following concerns.

  • Although there is some margin in the height, the board mounting area is insufficient.
  • Parts do not fit on the board without reducing their number.
  • A space for adding noise suppression parts needs to be secured.
Panasonic's capacitor design support
Panasonic's capacitor design support

Panasonic supports the optimal design utilizing hybrid capacitors to address these problems in power supply circuits for control system applications such as engine ECUs and ADAS domain control units (DCUs), as well as for motor system applications such as electric compressors, electric pumps, and EPS.

Proposal case using hybrid capacitors

This section introduces a proposal case for replacing the conventional three output capacitors with a single capacitor for the purpose of reducing the size of the board of "the 12 V output DC/DC power supply" used in control system applications such as engine ECUs and ADAS DCUs.

Circuit diagram
Circuit diagram
Capacitor specifications
Capacitor specifications
Fig. Circuit diagram of 12 V output DC/DC power supply and capacitor specifications

When considering the replacement of output capacitors, it is necessary to consider the impact on electrical characteristics caused by changes in the capacitor's capacitance values, ESR values, and ESL values as well as various constraints in power supply design. We propose optimal products that satisfy the power supply characteristics and design constraints from our broad lineup of hybrid capacitors. In the DC/DC power supply circuit shown in the figure above, three ZC series hybrid capacitors rated at 25V 330μF, size10×10.2mm, ripple current of 2.0Arms, ESR 20mΩare used in parallel as output capacitors.
When the number of parts must be reduced to save space on the board, products with a capacitance of 560 uF or more should be considered as candidates. Regarding our products, ZS (560 uF), ZU (560 uF), ZSU (560 uF, 1000 uF), and ZKU (560 uF) are listed as candidates. In this proposal case, we introduce an example of consideration of a replacement with ZSU (1000 uF), which is expected to have the most reduction effect.

 

The figure below shows the simulation evaluation results of the power supply output voltage at a sudden load change.
A single ZSU series hybrid capacitor（rated at 25V 1000μF、sizeφ10×16.5mm, ripple current 4.0Arms, ESR 11mΩ）demonstrates the same performance of power supply voltage as the current design in both the rise and fall of load fluctuations, which indicates that replacement with a reduction in the board mounting area by about 66% is possible.

Fig. Simulation evaluation results of load transient response at a sudden load change
Fig. Simulation evaluation results of load transient response at a sudden load change

When the customer carries out the design consideration described above by themselves, they must find an appropriate product from a large number of capacitors based on the specifications, which takes a lot of time and effort. In addition, consideration only based on numerical values of the specifications tends to result in choosing an overspec product, which may not achieve optimization after all. Although optimization can be achieved by prototyping and validating circuits, this requires a lot of effort, time, and cost.

Summary

When customers consider hybrid capacitors, Panasonic can propose the most suitable product based on the conditions in which the power supply circuit is used provided by the customers. Such proposals can be made only by a manufacturer that understands the characteristics of the product that are not shown in the specification table. While utilizing simulation tools and other items, we will continue to support the optimization design for our customers' applications, contributing to a reduction of effort, time, and cost.

Related product information

Related information

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